• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1572-1574
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• 2000

In this paper, study on the properties of the thermal degradated epoxy resin which is used in cast resin transformer is performed to investigate the problems of the decreasing insulation characteristics and crack in the cast resin transformer. In the test, contact angle, weight loss, surface resistivity and relative dielectric constant are measured. As the results of the above measurements, the epoxy resin has increased to 150$^{\circ}C$ in the contact angle and surface resistivity but at the above 150$^{\circ}C$ the values have decreased. The relative dielectric constants have increased in the thermal treated samples with the degradation temperature. Consequently, the insulation properties of the epoxy resin which is used in cast resin transformer have increased by the 150$^{\circ}C$ but decreased in the above 150$^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.857-860
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• 2000

The objective of this paper is to demonstrate degradation phenomena through DC degradation tests and predicts degradation phenomena as a function of time from the tests. The ZnO varistor used in this investigation were fabricated by standard ceramic techniques. Especial, these were sintered in nitrogen atmosphere, at 2 h, for $1300^{\circ}C$. The conditions of DC degradation test were 115$\pm$$2^{\circ}C$for 0, 2, 4, and 8 h, respectively. To demonstrate the degradation phenomena of ZnO varistors, Voltagecurrent analyses were performed before and after the degradation test, and frequency analyses were used with the time of the degradation tests. It was found that the degradation occurred in not grain but grain boundary and the degradation behavior of varistors was unsymmetrically degraded with the direction of tests.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.88-92
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• 2020

Thermal effects in bulk and SOI FinFETs are briefly reviewed herein. Different techniques to measure these thermal effects are studied in detail. Self-heating effects show a strong dependency on geometrical parameters of the device, thereby affecting the reliability and performance of FinFETs. Mobility degradation leads to 7% higher current in bulk FinFETs than in SOI FinFETs. The lower thermal conductivity of SiO₂ and higher current densities due to a reduction in device dimensions are the potential reasons behind this degradation. A comparison of both bulk and SOI FinFETs shows that the thermal effects are more dominant in bulk FinFETs as they dissipate more heat because of their lower lattice temperature. However, these thermal effects can be minimized by integrating 2D materials along with high thermal conductive dielectrics into the FinFET device structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.389-392
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• 1997

Glutaronitrile(GN) was introduced to diglycidyl ether of bisphenol A(DGEBA)/ 4,4'-methylene dianiline(MDA) system to improve toughness. Effects of GN contents on thermal decomposition of epoxy resin system were investigated. To study the characteristics of thermal decomposition, thermo-gravimetric analysis(TGA) and Kissinger equation were used. Thermal degradation temperatures were about 365$^{\circ}C$ regardless of GN contents. Activation energies of thermal decomposition in epoxy resin system were almost constant below 10 phr and decreased above 15 phr.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.75-78
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• 2002

In this paper, we investigated the change of wettability, surface potential decay and surface resistivity caused by thermal-treated and plasma-treated FRP respectively for finding out the influence of electrical characteristics on the surface of polymer composites. For the change of wettability, the contact angle of thermal-treated specimen with the high temperature of 200$^{\circ}C$ increased. But that of plasma-treated specimen decreased. The characteristic of surface potential decay shows the tendency of the remarkable decrease on plasma-treated specimens, but no difference on thermal-treated specimen compared with untreated one. Also, for the surface resistivity, it shows the same trend compared with the change of contact angle. We can conclude that the degradation phenomena of epoxy surface are dominated by the induction of hydrophilicity and hydrophobicity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.459-462
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• 2002

The conventional thermal insulator and power transformer testing is widely used in surface aging measurement of outside insulator because those testing can carry out very short time in Lab testing. Also thermal testing is able to offer the standard judgement of relative degradation level of outside HV machine. There it is very useful method compare to previous conventional thermal testing method and effective Lab testing method. But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IRR-camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis. In this study, thermal testing of Power transformer is measured with partial temperature distribution in real time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.69-72
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• 2002

The conventional thermal insulator and power transformer testing is widely used in surface aging measurement of outside insulator because those testing can carry out very short time in Lab testing. Also thermal testing is able to offer the standard judgement of relative degradation level of outside HV machine. There it is very useful method compare to previous conventional thermal testing method and effective Lab testing method. But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IRR-camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis. In this study, thermal testing of power transformer is measured with partial temperature distribution in real time.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1543-1545
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• 1997

In this work, properties of FRP insulation materials by thermal-accelerated degradation were investigated. Usually, most degradations cause the hydrophilic to decrease the contact angle and surface properties. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of small-molecules rather than chain scission and oxidation. Hydrophobic introduction in thermal-degradated FRP caused the increase of electrical insulation on treated FRP surface. But, Tensile strength decreased steeply on FRP being exposed higher temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.479-482
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• 1999

Cured epoxy resins are extensively used for the electrical insulation in high-voltage equipments. The bisphenol A-based epoxy resins lured with azine show, especially, good thermal properties and mechanical resistances. For the technical and economic reasons, varing amount of inorganic fillers are added to endow the required special properties. In the large generators and motors of power plants, epoxy insulation is disclosed to the harsh conditions like the superheated steam and abrupt temperature variation. Hygrothermal aging at elevated temperatures tends to induce degradation in epoxy resins. To predict the effect of this degradation in DGEBA/MDA/SN/zeolite system, we proceeded the forced moisture absorption experiment using the autoclave. The thermal properties of the untreated and treated specimens were analyzed by DSC and TGA under the nitrogen flowing condition. The moisture absorption results showed a weight increase during hygrothermal aging at 1207. At the initial aging period, the system leaded to more or less postcuring but more prolonged environmental aging leaded the discoloration of specimen and lowering the T$_{g}$./.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.123-127
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• 2011

To clarify the relations of optical properties to the main factors responsible for the loss and damage of luminous efficacy, a 20 min turn-on/turn-off test for 2,000 h for a ceramic metal halide lamp is conducted. The corrosion rates of the arc tube wall and electrode are estimated based on thermal stress. Wall blackening is attributed to the tungsten being transported from the hot electrode tips to the relatively cold arc tube wall. Furthermore, the grain boundaries of the arc tube are changed by the degradation. Distortion of the electrode is observed, and the ignition and the driving voltage of the load both increase. Finally, the color rendering index and the color coordinates are changed after the degradation. The luminous flux and the intensity of the luminous distribution are decreased significantly.